Subject: Re: [PATCH v4 06/15] mm/execmem, arch: convert simple overrides of module_alloc to execmem

From: Mike Rapoport <[email-masked]>
Date: Sun, 14 Apr 2024 10:26:47 +0300

On Thu, Apr 11, 2024 at 10:53:46PM +0200, Sam Ravnborg wrote:
> Hi Mike.
> 
> On Thu, Apr 11, 2024 at 07:00:42PM +0300, Mike Rapoport wrote:
> > From: "Mike Rapoport (IBM)" <[email-masked]>
> > 
> > Several architectures override module_alloc() only to define address
> > range for code allocations different than VMALLOC address space.
> > 
> > Provide a generic implementation in execmem that uses the parameters for
> > address space ranges, required alignment and page protections provided
> > by architectures.
> > 
> > The architectures must fill execmem_info structure and implement
> > execmem_arch_setup() that returns a pointer to that structure. This way the
> > execmem initialization won't be called from every architecture, but rather
> > from a central place, namely a core_initcall() in execmem.
> > 
> > The execmem provides execmem_alloc() API that wraps __vmalloc_node_range()
> > with the parameters defined by the architectures.  If an architecture does
> > not implement execmem_arch_setup(), execmem_alloc() will fall back to
> > module_alloc().
> > 
> > Signed-off-by: Mike Rapoport (IBM) <[email-masked]>
> > ---
> 
> This code snippet could be more readable ...
> > diff --git a/arch/sparc/kernel/module.c b/arch/sparc/kernel/module.c
> > index 66c45a2764bc..b70047f944cc 100644
> > --- a/arch/sparc/kernel/module.c
> > +++ b/arch/sparc/kernel/module.c
> > @@ -14,6 +14,7 @@
> >  #include <linux/string.h>
> >  #include <linux/ctype.h>
> >  #include <linux/mm.h>
> > +#include <linux/execmem.h>
> >  
> >  #include <asm/processor.h>
> >  #include <asm/spitfire.h>
> > @@ -21,34 +22,26 @@
> >  
> >  #include "entry.h"
> >  
> > +static struct execmem_info execmem_info __ro_after_init = {
> > +	.ranges = {
> > +		[EXECMEM_DEFAULT] = {
> >  #ifdef CONFIG_SPARC64
> > -
> > -#include <linux/jump_label.h>
> > -
> > -static void *module_map(unsigned long size)
> > -{
> > -	if (PAGE_ALIGN(size) > MODULES_LEN)
> > -		return NULL;
> > -	return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
> > -				GFP_KERNEL, PAGE_KERNEL, 0, NUMA_NO_NODE,
> > -				__builtin_return_address(0));
> > -}
> > +			.start = MODULES_VADDR,
> > +			.end = MODULES_END,
> >  #else
> > -static void *module_map(unsigned long size)
> > +			.start = VMALLOC_START,
> > +			.end = VMALLOC_END,
> > +#endif
> > +			.alignment = 1,
> > +		},
> > +	},
> > +};
> > +
> > +struct execmem_info __init *execmem_arch_setup(void)
> >  {
> > -	return vmalloc(size);
> > -}
> > -#endif /* CONFIG_SPARC64 */
> > -
> > -void *module_alloc(unsigned long size)
> > -{
> > -	void *ret;
> > -
> > -	ret = module_map(size);
> > -	if (ret)
> > -		memset(ret, 0, size);
> > +	execmem_info.ranges[EXECMEM_DEFAULT].pgprot = PAGE_KERNEL;
> >  
> > -	return ret;
> > +	return &execmem_info;
> >  }
> >  
> >  /* Make generic code ignore STT_REGISTER dummy undefined symbols.  */
> 
> ... if the following was added:
> 
> diff --git a/arch/sparc/include/asm/pgtable_32.h b/arch/sparc/include/asm/pgtable_32.h
> index 9e85d57ac3f2..62bcafe38b1f 100644
> --- a/arch/sparc/include/asm/pgtable_32.h
> +++ b/arch/sparc/include/asm/pgtable_32.h
> @@ -432,6 +432,8 @@ static inline int io_remap_pfn_range(struct vm_area_struct *vma,
> 
>  #define VMALLOC_START           _AC(0xfe600000,UL)
>  #define VMALLOC_END             _AC(0xffc00000,UL)
> +#define MODULES_VADDR           VMALLOC_START
> +#define MODULES_END             VMALLOC_END
> 
> 
> Then the #ifdef CONFIG_SPARC64 could be dropped and the code would be
> the same for 32 and 64 bits.
 
Yeah, the #ifdef there can be dropped even regardless of execmem.
I'll add a patch for that.

> Just a drive-by comment.
> 	Sam

-- 
Sincerely yours,
Mike.